This application is a national stage of PCT/EP99/00221 filed Sep. 10, 2001 and based upon Austrian national application GM 601/98 filed Sep. 11, 1998 under the International Convention.
The invention concerns an automobile wheel unit with a tire inflation system consisting of a hub rotatably mounted in a wheel carrier and an axially-removable wheel, whereby the hub is connected via a rotational drive means to a tire inflation system, and the air flow is connected to the wheel via overlapping axial holes in the hub and wheel, and the axial hole in the wheel terminates in a chamber containing a seal.
Such tire inflation systems serve to adjust the air pressure in tires. The required air connection between the hub and removable wheel is made via the overlapping axial holes. To prevent the air from escaping from the wheel when it is removed, a seal is usually provided in practice for wheeled tanks that is screwed against the mouth of the axial hole when the wheel is removed. This is impractical and easily forgotten.
The object of the invention is to provide an air connection between the hub and wheel that independently closes when the wheel is removed so that pressure is not lost, even briefly.
This object is achieved according to the invention in that:
a) a spring is provided that presses the seal toward the mouth of the axial hole,
b) a moveable tube piece is provided in the axial hole in the wheel that has side openings inside the chamber, and
c) a sealing ring is inserted in the axial hole in the wheel that contact the tube piece.
The seal in a) is a spring-loaded valve that is tightly sealed by the pressure in the chamber. When the wheel is connected to the hub, the tube piece in b) presses the seal into an open position, and its side openings ensure that the air connection between the wheel and hub remains intact. The sealing ring in c) ensures that no pressure is lost.
In a preferred development of the invention, the spacing of the sealing ring from the mouth of the axial hole in the wheel is greater than the axial extension of the side openings of the tube piece. Accordingly when the wheel is removed, the tube piece is pressed into the axial hole of the wheel, and the side openings are inserted into the axial hole which does not pass the sealing ring. This ensures that no air escapes from the wheel when it is removed.
In one embodiment, the tube piece is fixed to the hub. In an alternative embodiment, the tube piece is fixed to or forms a single piece with the seal.